Weapon hacking: making this one piece, 3D printed mini crossbow at home

Mar.12, 2013

Back in the old days, around the 3rd century, crossbows played a significant role in the warfare of East Asia, Europe and the Mediterranean. However making such a weapon could take a team of skilled workers many weeks. But today, with 21st century technology, Chris from Trench Physics, a real maker, could just fabricate it on his 3D printer in under a day.

Nowadays crossbows are used primarily for shooting sports and hunting. For Chris the challenge was to make something functional, and make it fully printable. The only part that is not 3D printed is the string, it is a chopstick or something similar.

The most interesting part is that the crossbow is only a single piece of plastic. After making a few test prints with strips of different thicknesses, Chris chose to use 2mm wall thickness for keeping the best flexibility and durability.

When printing he set Slic3r to infill the material in a concentric pattern to make it flexible in the dimensions. The bow was printed with the handle side up and with support material.

(Images credit: Chris from Trench Physics)

Chris' biggest challenge was the trigger. Originally he planned to take some design from google images but they were all difficult parts with too many moving parts. Chris wanted to build something simple without assembly needed. After a few tests he decided to use the plastic as a spring, and it works pretty well.

Now you can download the 3D files for the bow on Thingiverse to make your own mini-crossbow.